Carotenoid from green algae shows ‘potent’ anti-fat activity

By Stephen Daniells Nutra Ingredients USA

A carotenoid from green algae called siphonaxanthin may inhibit the development of fat cells and the build-up of fat in fat tissue, suggests new research from Japan. The compound could be a novel ingredient for use in weight management supplements, said the researchers.

Siphonaxanthin was found to significantly outperform a host of other carotenoids, including beta-carotene, fucoxanthin, lutein, and zeaxanthin in inhibiting the formation of fat cells and the build-up of fat in those cells, report researchers from Kyoto University and Shijonawate Gakuen University.

“Our results indicate that siphonaxanthin may be a useful dietary supplement for the regulation of lipid accumulation in adipose tissue,” wrote the researchers in the Journal of Nutrition .

“To our knowledge, we are the first to suggest such a role for siphonaxanthin in adipogenesis, although further studies are required to understand its mechanism and metabolism.”

The study used in vitro and mice to evaluate the effects, and more research is needed to verify the safety and efficacy of the ingredient in humans as a tool for weight management.

The search for new functional compounds
With obesity rates continuing to increase, a lot of research is focusing on potential nutritional ingredients to help slow expanding waistlines.

“In recent years, marine algae have served as a valuable source for functional compounds with potentially beneficial health effects,” explained the Japanese researchers.

“Among these compounds from marine algae, natural carotenoids have attracted a great deal of attention because of their diverse and beneficial bioactivities, such as antioxidant, anticancer, anti-inflammatory, and anti-obesity activities.”

Siphonaxanthin, a xanthophyll and one of the oxidative metabolites of lutein, can be found in green algae such as Codium fragile, Caulerpa lentillifera, and Umbraulva japonica.

Previous research by the same research group suggested a potential anti-cancer activity for the compound, and they have now expanded this to an investigation into the compound’s potential fat-fighting activity.

Study details
The researchers used two experimental systems: A 3T3-L1 cell culture system and diabetic/obese KK-Ay mice.

For the cell study, cells were incubated with a solution of siphonaxanthin to assess fat build-up and gene expression, and results showed a dose-dependent effect on fat accumulation in the cells: “Siphonaxanthin significantly suppressed lipid accumulation at non-cytotoxic concentrations of 2.5 and 5 micromoles per liter by 29% and 43%, respectively,” they wrote. The carotenoid was also found to affect the expression of key genes linked to the formation of fat cells.

Data from the mouse study indicated that a daily 1.3 mg dose of siphonaxanthin for six weeks was associated with a 13% reduction in white adipose tissue weight in the animals.

In addition, the carotenoid reduced the build up of fat, and increased fat burning in fat tissue.

The key is in the structure

“In this study, we screened 12 carotenoids to evaluate their anti-adipogenesis activity and identified siphonaxanthin as a compound that potently inhibits adipogenesis,” wrote the researchers. “It is assumed that the antiadipogenic activity of siphonaxanthin is likely associated with its unique structure.” [The structure is shown above]

The researchers explained that, while siphonaxanthin and fucoxanthin have similar structures and are both considered ‘keto-carotenoids’, the former has a hydroxyl group at the C-19 position, whereas fucoxanthin does not.

“We assume that the presence of both the keto group and the hydroxyl group may be important for the inhibitory effect of siphonaxanthin on adipocyte differentiation,” they said.